Methods and apparatus for controlling the size of an edge exclusion zone of a substrate

ABSTRACT

In some embodiments, a method of controlling a width of an edge exclusion zone of a substrate is provided. The method includes determining a range of angles over which to rotate a polishing head; rotating the polishing head over the determined range of angles to achieve a preset width for an edge exclusion zone of the substrate; and polishing an edge of the substrate with the polishing head. Numerous other aspects are provided.

The present application claims priority from U.S. Provisional PatentApplication Ser. No. 60/939,209, filed May 21, 2007, entitled “METHODSAND APPARATUS FOR CONTROLLING THE SIZE OF AN EDGE EXCLUSION ZONE OF ASUBSTRATE” (Attorney Docket No. 11987/L) which is hereby incorporated byreference herein in its entirety.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application is related to the following commonly-assigned,co-pending U.S. Patent Applications, each of which is herebyincorporated herein by reference in its entirety for all purposes:

U.S. patent application Ser. No. 11/299,295 filed on Dec. 9, 2005 andentitled “METHODS AND APPARATUS FOR PROCESSING A SUBSTRATE” (AttorneyDocket No. 10121);

U.S. patent application Ser. No. 11/298,555 filed on Dec. 9, 2005 andentitled “METHODS AND APPARATUS FOR PROCESSING A SUBSTRATE” (AttorneyDocket No. 10414);

U.S. Patent Application Ser. No. 60/939,351, filed May 21, 2007,entitled “METHODS AND APPARATUS FOR POLISHING A NOTCH OF A SUBSTRATEUSING AN INFLATABLE POLISHING WHEEL” (Attorney Docket No. 10674/L);

U.S. Patent Application Ser. No. 60/939,353, filed May 21, 2007,entitled “METHODS AND APPARATUS FOR FINDING A SUBSTRATE NOTCH CENTER”(Attorney Docket No. 11244/L);

U.S. Patent Application Ser. No. 60/939,343, filed May 21, 2007,entitled “METHODS AND APPARATUS TO CONTROL SUBSTRATE BEVEL AND EDGEPOLISHING PROFILES OF EPITAXIAL FILMS” (Attorney Docket No. 11417/L);

U.S. Patent Application Ser. No. 60/939,219, filed May 21, 2007,entitled “METHODS AND APPARATUS FOR POLISHING A NOTCH OF A SUBSTRATEUSING A SHAPED BACKING PAD” (Attorney Docket No. 11483/L);

U.S. Patent Application Ser. No. 60/939,342, filed May 21, 2007,entitled “METHODS AND APPARATUS FOR REMOVAL OF FILMS AND FLAKES FROM THEEDGE OF BOTH SIDES OF A SUBSTRATE USING BACKING PADS” (Attorney DocketNo. 11564/L);

U.S. Patent Application Ser. No. 60/939,350, filed May 21, 2007,entitled “METHODS AND APPARATUS FOR USING A BEVEL POLISHING HEAD WITH ANEFFICIENT TAPE ROUTING ARRANGEMENT” (Attorney Docket No. 11565/L);

U.S. Patent Application Ser. No. 60/939,344, filed May 21, 2007,entitled “METHODS AND APPARATUS FOR USING A ROLLING BACKING PAD FORSUBSTRATE POLISHING” (Attorney Docket No. 11566/L);

U.S. Patent Application Ser. No. 60/939,333, filed May 21, 2007,entitled “METHODS AND APPARATUS FOR SUBSTRATE EDGE POLISHING USING APOLISHING ARM” (Attorney Docket No. 11567/L);

U.S. Patent Application Ser. No. 60/939,212, filed May 21, 2007,entitled “METHODS AND APPARATUS FOR IDENTIFYING A SUBSTRATE EDGE PROFILEAND ADJUSTING THE PROCESSING OF THE SUBSTRATE ACCORDING TO THEIDENTIFIED EDGE PROFILE” (Attorney Docket No. 11695/L);

U.S. Patent Application Ser. No. 60/939,337, filed May 21, 2007,entitled “METHODS AND APPARATUS FOR HIGH PERFORMANCE SUBSTRATE BEVEL ANDEDGE POLISHING IN SEMICONDUCTOR MANUFACTURE” (Attorney Docket No.11809/L); and

U.S. Patent Application Ser. No. 60/939,228, filed May 21, 2007,entitled “METHODS AND APPARATUS FOR POLISHING A NOTCH OF A SUBSTRATE BYSUBSTRATE VIBRATION” (Attorney Docket No. 11952/L).

FIELD OF THE INVENTION

The present invention relates generally to substrate processing, andmore particularly to methods and apparatus for polishing an edge of asubstrate.

BACKGROUND OF THE INVENTION

In preparing a substrate for semiconductor device manufacturing, theedge of the substrate is generally cleaned and/or polished. Typically, abuffer zone or ‘edge exclusion zone’ is provided between the deviceregion and the edge of the substrate to protect the device region. Dueto increasingly stringent requirements, precise control of the width ofthe edge exclusion zone has become a priority in order to optimizedevice yield. It has proven difficult to provide such precise controlover the width of the edge exclusion zone. Accordingly, improved methodsand apparatus for controlling polishing of an edge of a substrate toachieve control over the width of an edge exclusion zone are desired.

SUMMARY OF THE INVENTION

In a first aspect of the invention, a method of controlling a width ofan edge exclusion zone on a substrate is provided. The method includesdetermining a range of angles over which to rotate a polishing head;rotating the polishing head over the determined range of angles toachieve a preset width for an edge exclusion zone of the substrate; andpolishing an edge of the substrate with the polishing head.

In another aspect of the invention, a method of controlling a width ofan edge exclusion zone on a substrate is provided. The method includesdetermining a radial position at which to place a polishing head withrespect to a substrate so as to achieve a preset width of an edgeexclusion zone for the substrate; moving the polishing head to thedetermined radial position; and polishing the substrate with thepolishing head.

In yet another aspect of the invention, a method of controlling a widthof an edge exclusion zone on a substrate is provided. The methodincludes providing a polishing head having a head spacer and a backingroller coupled to the head spacer at an off-center position and adaptedto apply a polishing tape to a substrate during polishing; and applyingthe polishing tape to an edge exclusion zone of the substrate using thepolishing head during polishing.

In another aspect of the invention, a system for controlling a width ofan edge exclusion zone on a substrate is provided. The system comprisesa polishing head having a head spacer, wherein the polishing head isadapted to contact the edge of a substrate; a backing pad coupled to thehead spacer at an off-center position; a polishing arm coupled to thepolishing head; and a controller adapted to operate the polishing headand polishing arm to control an edge exclusion zone of the substrate.

Other features and aspects of the present invention will become morefully apparent from the following detailed description, the appendedclaims and the accompanying drawings.

BRIEF DESCRIPTION OF THE FIGURES

FIG. 1 is a schematic cross-sectional view of an edge of an exemplarysubstrate.

FIG. 2 is a schematic top view of an exemplary system for edge polishingaccording to an embodiment of the present invention.

FIG. 3 is a perspective view of an edge polishing apparatus according toan embodiment of the present invention.

FIG. 4 is a close-up perspective view of a polishing head according toan embodiment of the present invention.

FIG. 5A is a schematic cross-sectional view illustrating a method ofcontrolling the width of the edge exclusion zone via the angularrotation of the polishing head according to an embodiment of the presentinvention.

FIG. 5B is a schematic cross-sectional view illustrating a method ofcontrolling the width of the edge exclusion zone via the position of thepolishing head over the substrate according to an embodiment of thepresent invention.

FIG. 5C is a schematic cross-sectional view illustrating a method ofcontrolling the width of the edge exclusion zone via a head spaceroffset according to an embodiment of the present invention.

FIG. 6 is a close-up perspective view of a head spacer according to anembodiment of the present invention.

FIG. 7 is a flow chart of an exemplary method of controlling the widthof an edge exclusion zone via the angular rotation of a polishing headaccording to the present invention.

FIG. 8 is a flow chart of an exemplary method of controlling the widthof an edge exclusion zone via the position of a polishing head over asubstrate according to the present invention.

FIG. 9 is a flow chart of a method of controlling the width of an edgeexclusion zone via a head spacer offset according to the presentinvention.

DETAILED DESCRIPTION

The present invention provides improved methods and systems forcontrolling a width of an edge exclusion zone on a substrate. The widthof the edge exclusion zone of a substrate may be different for differentelectronic device manufacturers. The edge exclusion zone is typicallypositioned between a production or device region of the substrate andthe substrate edge. While it is often desirable to polish the substrateedge, polishing the substrate in production or device region isundesirable. Therefore, the present invention provides methods andsystems to control the width (e.g., polished width) of the edgeexclusion zone of a substrate.

In one embodiment of the invention, precise control over the width of anedge exclusion zone may be provided by angularly translating (‘rocking’) a polishing head at different angles (‘rocking angles’), where alarger angular sweep causes a larger amount of material to be removedduring polishing, and accordingly, an increased exclusion zone width.

In another embodiment of the invention, precise control over the widthof an edge exclusion zone may be provided by controlling the position atwhich a polishing head applies polishing tape onto a substrate, and inparticular, by controllably moving a polishing arm, including thepolishing head, toward or away from the center the substrate. Movementof the polishing arm toward the center of the substrate may increase thewidth of the edge exclusion zone and movement of the polishing arm awayfrom the center of the substrate may decrease the width of the edgeexclusion zone.

In yet another embodiment of the invention, precise control over thewidth of an edge exclusion zone may be provided by offsetting a positionof a backing pad (e.g., pad, bladder, roller on the like) in thepolishing head so as to control the position of the backing pad relativeto the substrate surface. In some embodiments, the offsetting may beprovided using an off-center polishing head spacer element. In one ormore embodiments, these methods may be used to control the width of theexclusion zones to sub-millimeter accuracy.

Turning to FIG. 1, a schematic cross-sectional view of a portion of asubstrate 100 is provided. The substrate 100 may include two majorsurfaces 102, 102′, and an edge 104. Each major surface 102, 102′ of thesubstrate 100 may include a device region 106, 106′ upon which devicesmay be fabricated, and an exclusion region 108, 108′ (termed ‘edgeexclusion zone’ herein) upon which device fabrication is not meant tooccur. (Typically however, only one of the two major surfaces 102, 102′will include a device region and an exclusion region). The edgeexclusion zones 108, 108′ may serve as a buffer between the deviceregions 106, 106′ and the edge 104. The edge 104 of a substrate 100 mayinclude an outer edge 110 and bevels 112, 114. The bevels 112, 114 maybe located between the outer edge 110 and the exclusion regions 108,108′ of the two major surfaces 102, 102′ and may have surfaces alignedat an angle with respect to the major surfaces 102, 102′. In an edgepolishing process, the bevels 112, 114 and/or the edge exclusion zones108, 108′ may be polished to remove defects or contaminants, to reducefilm thickness and more generally to improve surface uniformity.

Because the edge exclusion zones 108, 108′ occupy space unavailable fordevice fabrication, the width of the edge exclusion zones 108, 108′tends to be minimized to increase product yield. However, if the widthsof the edge exclusion zones 108, 108′ are too small, the zones 108, 108′may no longer operate adequately as buffers, and the device regions 106,106′ may be accidentally polished or otherwise adversely affected byedge polishing processes due to the close proximity between the edge 104and the device regions 106, 106′. Moreover, the optimal width of theedge exclusion zones 108, 108′ may vary based on the size and type ofsubstrate, the fabrication processes to be performed on the substrate,and/or other end-user specifications, which may be stringent. Thus, itis useful to have precise control over the width of the edge exclusionzones 108, 108′ to avoid unnecessary losses in yield while stillmaintaining the buffering function of the zones 108, 108′, and also tomeet any other end-use requirements.

FIG. 2 shows a top view of an exemplary edge polishing system or‘module’ 200 according to the present invention. The edge polishingmodule 200 may be integrated within a larger substrate preparationsystem (not shown) for use in an electronic device manufacturingfacility. For example, the substrate preparation system may include afactory interface for receiving new, unprepared substrates, and one ormore cleaning modules for removing any dust or particles from thesubstrate 100 in addition to polishing modules, such as the edgepolishing module 200. The substrate preparation system may be used tocondition substrates for subsequent processes, such as etching,deposition, etc., or after such processes.

The edge polishing module 200 of FIG. 2 may include a housing 201 inwhich one or more edge polishing apparatuses 202, 204, 206 arepositioned. Although the embodiment shown includes three (3) polishingapparatuses, other numbers of apparatuses may be used (e.g., 1, 2 ormore than 3). The edge polishing apparatuses 202, 204, 206 arepositioned surrounding a central platform 208 (shown in FIG. 3) uponwhich the substrate 100 may be mounted and supported. The centralplatform 208 may be rotatable by a driver 211 (e.g., motor, gear, belt,chain, etc.) (also shown in FIG. 3) and may include a vacuum chuck orother mechanism for holding the substrate 100 in place during rotationof the central platform 208. In the depicted embodiment, the substrate100 is disk-shaped having major surfaces oriented in the horizontalplane. However, in alternative embodiments, the substrate 100 may haveother shapes and orientations.

Each edge polishing apparatuses 202, 204, 206 may be coupled to, andsupplied with, an abrasive polishing tape by a corresponding set ofpolishing tape spools 212, 214, 216. Each set of polishing tape spools212, 214, 216 may include a supply spool and a take-up spool (shown inFIG. 3). The supply spools may store unused polishing tape available tobe unwound and pulled into the corresponding polishing apparatuses 202,204, 206 positioned adjacent to the substrate 100, while the take-upspools may be adapted to receive used and/or worn polishing tape. One orboth of the supply and take-up spools may be indexed to preciselycontrol the amount of polishing tape that is advanced to thecorresponding edge polishing apparatuses 202, 204, 206.

The edge polishing module 200 may also include a controller 220 (e.g., asoftware driven computer, a programmed processor, a microcontroller, agate array, a logic circuit, an embedded real time processor, etc.)adapted to direct the operation of the components of the edge polishingmodule including the polishing apparatuses 202, 204, 206, the driver211, and/or sets of spools 212, 214, 216. In one or more embodiments,each polishing apparatus 202, 204, 206 may be equipped with its owncontroller. The controller 220 may include or be coupled to memoryresources (e.g., DRAM, ROM, flash memory, optical disk, local areanetwork (LAN) storage) (not shown). In one or more embodiments, thecontroller 220 may be adapted to access data related to operation of theedge polishing module 200 which may be stored in query-accessibledatabases stored within the memory resources.

In addition, the edge polishing module 200 may include one or moresensors (e.g., optical sensors 300 such as light sources and detectorssuch as photometers) (not shown) adapted to measure the width of theedge exclusion zones 108, 108′ on the substrate 100. For example, thesensor 300 may direct a light beam toward the edge exclusion zone of thesubstrate 100. The amount of light reflected back to and detected by thesensor 300 may determine a width of the edge exclusion zone of thesubstrate. Alternatively, a camera may directly measure the width of theedge exclusion zone. Further, a camera may image the substrate and imageprocessing software may determine the width of the edge exclusion zonebased on the image. Any suitable measurement system may be used.

Each edge polishing apparatus 202, 204, 206 may be adapted to load thepolishing tape forcibly into contact with the edge 104 of the substrate100 when supplied with polishing tape from corresponding sets of spools212, 214, 216, as described in greater detail below. The friction (e.g.,abrading contact) between the polishing tape 306 (shown in FIG. 3) andthe substrate edge 104 may include the torque exerted during rotation ofthe substrate 100 against the polishing tape 306 and the force exertedin pressing the polishing tape 306 onto the edge 104 of the substrate100. In some embodiments, the combined force at the point(s) of contactmay range from about 0.5 lbs. to about 2.0 lbs. Other amounts of forcemay be used.

Turning to FIG. 3, a schematic view of an edge polishing apparatus,e.g., 202, is depicted. The apparatus 202 may include a polishing arm301 aligned in the horizontal plane approximately tangential to the edge104 of the substrate 100. The polishing arm 301 may be supported by aframe 303. In other embodiments, the polishing arm 301 may be aligneddifferently, for example, vertically, or at an angle with respect to thehorizontal plane. The polishing arm 301 may include a polishing headsection 304 (‘head’) adapted to receive the polishing tape 306 from thea set of spools including a supply spool 308 and a take-up spool 310,and to forcibly apply the polishing tape 306 to the edge 104 of thesubstrate 100 as the substrate 100 is rotated by the central platform208 or by some other mechanism (e.g., drive rollers). The spools 308,310 may be driven by one or more drivers (e.g., servo motors) which mayprovide both an indexing capability to allow a specific amount of unusedpolishing tape 306 to be advanced or continuously fed to the substrateedge 104, and a tensioning capability to allow the polishing tape 306 tobe stretched taught and to apply pressure to the substrate edge 104. Insome embodiments, the spools 308, 310 may be approximately 1 inch indiameter, hold about 500 inches of polishing tape 306, and may beconstructed from any suitable materials such as polyurethane, polyvinyldifluoride (PVDF), etc. Other materials and spool dimensions may beused. As shown in FIG. 3, the spools 308, 310 may be oriented verticallyso that the footprint occupied by the entire edge polishing module 200and polishing apparatus 202 may be minimized.

Additionally, the polishing tape 306 may further be pulled taught by oneor more tensioning rollers 312 positioned on the head 304 (as shown) orin other locations. The tensioning roller(s) 312 may be adapted to applya variable amount of tension to the substrate edge 104 so as to attainprecise control over an edge polishing process, which may be used tocompensate for different edge geometries and changes in the substrate100 as material is removed from the edge 104 and/or edge exclusion zones108, 108′.

In one or more embodiments, the polishing tape 306 may be made from manydifferent materials including aluminum oxide, silicon oxide, siliconcarbide, etc. Other materials may also be used. In some embodiments, theabrasives used may range from about 0.5 microns up to about 3 microns insize although other sizes may be used. Different widths of polishingtape 306 ranging from about 0.2 inches to about 1.5 inches may be used(although other widths may be used). In one or more embodiments, thepolishing tape 306 may be about 0.002 to about 0.02 of an inch thick,and be able to withstand about 1 to 5 lbs. of tension in embodimentsthat use a pad (described below), and from about 3 to about 8 lbs. oftension in embodiments without a pad. Other polishing tapes 306 havingdifferent thicknesses and strengths may be used.

Edge polishing may be performed using one or more polishing apparatuses(e.g., 202, 204, 206). In one or more embodiments, a plurality ofpolishing apparatuses (e.g., 202, 204, 206) may be employed, in whicheach polishing apparatus may have similar or different characteristicsand/or mechanisms. In the latter case, particular polishing apparatusesmay be employed for specific operations. For example, one or more of aplurality of polishing apparatuses may be adapted to perform relativelyrough polishing and/or adjustments while another one or more of theplurality of polishing apparatus may be adapted to perform relativelyfine polishing and/or adjustments. For example, in some embodiments, thevarious polishing apparatus 202, 204, 206, of the edge polishing module200 may support different types of polishing tape 306 (e.g., tapes ofdifferent abrasive grits) which may be used concurrently, in apredefined sequence, or at different times. The heads (e.g., 304) of thepolishing apparatus 202, 204, 206 may also be disposed in differentpositions to allow the supported tapes to polish different portions ofthe edge 104 of the rotating substrate 100. In this manner, polishingapparatuses (e.g., 202, 204, 206) may be used in sequence so that, forexample, a rough polishing procedure may be performed initially and afine polishing procedure may be employed subsequently to makeadjustments to a relatively rough polish, as needed, or according to apolishing recipe.

The plurality of polishing apparatuses (e.g., 202, 204, 206) may belocated in a single chamber or module (e.g., 200), or alternatively, oneor more polishing apparatuses may be located in separate chambers ormodules. Where multiple chambers are employed, a robot or another typeof transfer mechanism may be employed to move substrates between thechambers so that polishing apparatuses in the separate chambers may beused in series or otherwise.

The head 304 may be angularly translated around an axis tangential tothe substrate edge 104, so as to apply force onto the substrate edge 104at different angles. The angular translation may be oscillatory suchthat the head 304 ‘rocks’ back and forth over and under the substrateedge 104. For example, FIG. 4 shows a close-up perspective view of anexemplary polishing head 304 positioned to apply the polishing tape 306to the edge 104 of the substrate 100 according to an embodiment of thepresent invention. The head 304 may be coupled (e.g., rigidly) to thepolishing arm 301 of the polishing apparatus 202 via a rocker arm 402 (aportion of which is shown in FIG. 4) and/or other components of thepolishing arm 301 such as an actuator or load arm (not shown). The head304 includes a frame 401 coupled to the rocker arm 402 which supportstension rollers 406 (only one shown in the figure) adapted to receiveand tension the polishing tape 306 delivered from the supply spool 308.The polishing tape 306 may be fed to a backing roller 408 while it ispulled taught by the tension rollers 406. The backing roller 408 maycomprise a rotatable pad shaped in the form of a roller and may bepressed toward the substrate edge 104 (via an actuator, not shown). Thepressure on the backing roller 408 may cause the backing roller 408and/or the polishing tape 306 (or portions thereof) to contour to thesubstrate edge 104 during polishing. The backing roller 408 may providereduced friction to the polishing tape 306 in comparison to stationarybacking pads. However, other backing pads, rolling or stationary, may beused.

The backing roller 408 may be rotationally coupled to a head spacer 410(e.g., by a pin joint, bolts, etc.), which, in turn may be coupled tothe rocker arm 402. As depicted, the rocker arm 402 may have a c-shapedcross-section having an interior space in which the head spacer 410 maybe positioned. In some embodiments of the present invention, the backingroller 408 may be coupled to the head spacer 410 at an off-centerposition of the head spacer 410. This off-center coupling may provide anadditional degree of control over edge polishing, and in particular, thewidth of the edge exclusion zones 108, 108′ as discussed in greaterdetail below with reference to FIG. 6C.

The rocker arm 402 may be adapted to rotate around a longitudinal axistangential to the edge 104 of the substrate 100. The longitudinal axismay be coincident with the rotational axis of the backing roller 408 or,more preferably, may be positioned some distance therefrom so that whenthe head 304 is rotated at a sufficient rocking angle, the backingroller 408 may be angularly translated (as opposed to simply rotated)above or below the substrate 100. The present invention providesadjustability of the rocking angle and thereby provides control over theangular translation of the backing roller 408 (and thus, the polishingtape 306) with respect to the surface of the substrate 100 to bepolished. It has been found such adjustability enables precise controlover the level of polishing at or near the edge exclusion zones 108,108′.

The rocking angle may be defined with respect to a reference line (Y-Y′)(shown in FIG. 5A) along the frame 401 of the polishing head 304. In theembodiment of the polishing head 304 depicted in FIG. 4 the referenceline (Y-Y′) (shown in FIG. 5A) is aligned perpendicular to thelongitudinal rotational axis of the head 304. When the reference line isvertically aligned (e.g., when reference line (Y) is perpendicular tothe horizontal plane of substrate 100, as shown in FIG. 5A) with thebacking roller 408 pointed toward the substrate edge 104, the rockingangle is defined as zero. In FIG. 5A, a positive rocking angle may bedefined as a clockwise rotation from zero (indicated by the bold dashedcurved arrow in FIG. 5A) in which the backing roller 408 (or a portionthereof) is angularly translated over the top surface 102 of thesubstrate 100. A negative rocking angle may be defined as acounterclockwise rotation from zero in which the backing roller 408 (ora portion thereof) is angularly translated under the bottom majorsurface 102′ of the substrate 100. Thus, FIG. 4 depicts the head 304 ata negative rocking angle with the rolling pad 408 and portions of theframe 401 positioned beneath (and obscured by) the bottom major surface102′ of the substrate 100.

FIG. 5A is a schematic cross-sectional view illustrating an inventivemethod of controlling edge exclusion width by controlling the angularrotation of the polishing arm 301. As shown, when the head 304,including the rocking arm 402 and backing roller 408, is in the firstposition at an angle (θ₁) with respect to the (Y-Y′) line, the backingroller 408 and associated polishing tape (not shown) is positioned overthe bevel 112 portion of the substrate 100 and is not in position topolish the edge exclusion region 108 of the substrate 100. The rockerarm 402 may be rotated to sweep from the first position at angle θ₁ to asecond position at angle θ₂. As can be discerned, when the rocker arm402 is rotated to the second position at angle (θ₂) with respect to the(Y-Y′) line (shown in phantom), the backing roller 408 and associatedpolishing tape (not shown) are positioned directly over the edgeexclusion zone 108, and may be applied to polish the substrate 100 atthis position. In this manner, the angular sweep of the rocking arm 402and the polishing head 304 may determine the width of the edge exclusionzone 108. For example, by sweeping the head 304 from 60 degrees to 80degrees, as opposed to sweeping the head 304 from 60 degrees to 70degrees, a greater amount of material may be removed, and consequentlythe width of the edge exclusion zone 108 may be increased approximatelyone millimeter, for example.

The controller 220 may determine a suitable angular sweep to achieve apreset desired edge exclusion zone width based on known polishingprofiles, which relate expected (e.g., experimentally determined)amounts of material removed during polishing at various substratepositions to angular sweep. Such profiles may be stored, for example, inone or more databases accessible by the controller 220. The controller220 may then send control signals to operate the rocker arm 402, basedon the determined suitable angular sweep.

FIG. 5B is a schematic cross-sectional view illustrating an alternativemethod of controlling edge exclusion width via the position of thepolishing arm 301 over the substrate 100. The polishing arm 301 may bemoved, and/or rotated, such that the head 304 is moved in a radialdirection toward or away from the center of the substrate 100. As shownin FIG. 5B, a centerline (bold dashed line) of the head 304 (e.g.,backing roller 408) can be moved inwardly from a first position (X1) toa second position (X2), thereby moving the head 304 and backing roller408 (shown in phantom) closer to the center of the substrate 100. If,for example, position X1 represents a first end of the edge exclusionzone 108, the distance from X1 to X2 (Δ) may represent a correspondingchange (e.g., increase) in the polished width of the edge exclusion zone108 as the backing roller 408 and associated polishing tape (not shown)is applied to polish the edge exclusion zone 108 of the major surface102 of the substrate 100. In this manner, the distance that the head 304is moved in a radial direction may determine the width of the edgeexclusion zone 108. According to embodiments of this method, thecontroller 220 may control the movement and/or rotation of the polishingarm 301 and position of the head 304 to achieve the preset desiredexclusion zone width.

FIG. 5C is a schematic cross-sectional view illustrating an inventivemethod of controlling edge exclusion width via the polishing head spacer410 in an offset position. FIG. 6 is a perspective view of an exampleembodiment of the head spacer 410 according to the present invention.The head spacer 410 comprises a first section 602 and a second section604. The second section 604 may be conjoined longitudinally in astaggered fashion to the first section 602 at a first end (not shown)and having a free second end 606. The free end 606 may include anopening 608 adapted to receive and rotatably couple the backing roller408. In one or more embodiments, the opening 608 may be positionedoff-center transverse to the longitudinal direction (e.g., the directionin which the first and second sections 602, 604 of the head spacer 410are joined). In some embodiments, as shown in FIG. 5C, when the opening608 is positioned centrally on the free end 606 of the head spacer 410,the centerline of the backing roller 408 is positioned at a firstposition (X3) (shown in FIG. 5C). When the opening 608 is offset adistance (D) toward the center of the substrate 100, the centerline ofthe head moves a corresponding distance (D) to a position (X4) (shown inFIG. 5D) closer to the center of the substrate 100 (shown in phantom).Alternatively, the amount by which the first and second sections 602,604 are staggered may be adjusted while leaving the opening 608centrally positioned in the free end 606 of the head spacer 402 tosimilarly move the opening 608 by the distance (D). The distance (D) ofthe offset of opening 608 may cause a corresponding change (e.g.,increase) in the polished width of the edge exclusion zone 108, as thebacking roller 408 and associated polishing tape (not shown) are appliedto polish the edge exclusion zone 108. In this manner, the offsetdistance (D) of the opening 608 may determine the width or change inwidth of the edge exclusion zone 108.

It is noted that the change in the width of the edge exclusion zone 108may not precisely correspond to (e.g., may be different than) the offsetdistance (D), due, for example, to rotational and/or angular movementsof the polishing arm 301 and head 304 when applied to the substrate 100during polishing operations. Known profiles relating expected (e.g.,experimentally-determined) amounts of material removed during polishingat various offset distances (D) may be stored in one or more databases(not shown) accessible by the controller 220, and used to determinepositional adjustments, such as the rotational and positional changesdescribed above, that may be made to achieve the preset desiredexclusion zone width.

Accordingly, each of the methods described above may be used alone or incombination, and in sequence or concurrently, to achieve a presetdesired exclusion zone width.

FIG. 7 is a flow chart illustrating an example method 700 of controllingthe width of the edge exclusion zone via angular rotation of thepolishing head according to the present invention. In step S702, themethod 700 beings. In step S704, a desired edge exclusion zone width ispreset. A user may pre-set the edge exclusion zone width by inputting awidth value into the controller 220, or the pre-set edge exclusion zonewidth may be determined automatically, based on input values, such as,the substrate size and the type(s) of devices to be fabricated on thesubstrate 100. In step S706, a range of rocking angles (e.g., theangular sweep) of the polishing arm 301 and head 304 may be determinedby the controller 220, based on the preset edge exclusion zone width. Asnoted above, the controller 220 may access one or more databases havingpolishing profile information in making this determination. In stepS708, the controller 220 sends control signals to the polishing arm 301and head 304 to rotate at the determined rocking angles duringpolishing.

In step S710, it is determined, by the controller 220, whether the edgeexclusion zone width has been attained, or is within a tolerance rangeof being reached. The determination may be made by measuring the actualedge exclusion width, using sensors for example, and comparing themeasured edge exclusion zone width to the preset desired edge exclusionzone width, for example. Other measurement means may be used. If in stepS710, the edge exclusion width has not been attained, and is not withinthe tolerance range, the method proceeds to step S712, in which thecontroller 220 determines an adjustment to be made to the rocking anglerange of the polishing arm 301 and head 304 to attain the preset edgeexclusion zone width (e.g., based on a difference between a measuredexclusion zone width and the preset exclusion zone width). In step S714,the controller 220 sends control signals to the polishing arm 301 andhead 304 to operate at the adjusted range of rocking angles duringpolishing. After step S714, the method cycles back to step S710. If instep S710, it is determined, by the controller 220, that the edgeexclusion zone width has been attained, or is within a tolerance range,the method ends in step S716. In some embodiments, actual edge exclusionwidth is not checked for each substrate (e.g., is only checkedinitially, periodically or at some other time(s), if at all).

FIG. 8 is a flow chart illustrating an example method 800 of controllingthe width of the edge exclusion zone via the position of the polishingarm 301 over the substrate 100 according to the present invention. Instep S802 the method 800 beings. In step S804, a desired edge exclusionzone width is preset. As described above with respect to FIG. 7, a usermay pre-set the edge exclusion zone width by inputting a width valueinto the controller 220, or the pre-set edge exclusion zone width may bedetermined automatically, based on input values, such as, the substratesize and the type(s) of devices to be fabricated on the substrate 100.In step S806, a radial position of the polishing arm 301 and head 304,with respect to the substrate 100, is determined by the controller 220,based on the preset edge exclusion zone width. In step S808, thecontroller 220 sends control signals to the polishing arm 301 to moveand/or rotate the polishing arm 301 (e.g., in the horizontal plane),thereby moving the head 304, to the determined radial position.Polishing then is performed.

In step S810, it is determined, by the controller 220, whether the edgeexclusion zone width has been attained, or is within a tolerance rangeof being reached. The determination may be made by measuring the actualedge exclusion width, using sensors, for example, and comparing themeasured edge exclusion zone width to the preset desired edge exclusionzone width, for example. If in step S810, the edge exclusion width hasnot been attained, and is not within the tolerance range, the methodproceeds to step S812, in which the controller 220 determines anadjustment to be made to the radial position of the head 304, adapted toattain the preset edge exclusion zone width (e.g., based on a differencebetween a measured exclusion zone width and the preset exclusion zonewidth). In step S814, the controller 220 sends control signals to thepolishing arm 301 and head 304 to move to the adjusted radial position;and polishing is performed. After step S814, the method cycles back tostep S810. If in step S810, it is determined, by the controller 220,that the edge exclusion zone width has been attained, or is within atolerance range, the method ends in step S816. In some embodiments,actual edge exclusion width is not checked for each substrate (e.g., isonly checked initially, periodically or at some other time(s), if atall).

FIG. 9 is a flow chart illustrating an example method 900 of controllingthe width of the edge exclusion zone via a head spacer offset accordingto the present invention. In step S902 the method 900 beings. In stepS904, a desired edge exclusion zone width is preset. As described abovewith respect to FIGS. 7 and 8, a user may pre-set the edge exclusionzone width by inputting a width value into the controller 220, or thepre-set edge exclusion zone width may be determined automatically, basedon input values, such as, the substrate size and the type(s) of devicesto be fabricated on the substrate 100. In step S906, a head spacer 410,having an offset opening 608 adapted to couple to a backing roller 408,is provided, in which the offset distance (D) is comparable to the edgeexclusion width. In step S908, the controller 220 sends control signalsto operate the polishing arm 301 and head 304, with the backing roller408 at the offset position.

In step S910, it is determined, by the controller 220, whether the edgeexclusion zone width has been attained, or is within a tolerance rangeof being reached. The determination may be made by measuring the actualedge exclusion width, using sensors, for example, and comparing themeasured edge exclusion zone width to the preset desired edge exclusionzone width. If in step S910, the edge exclusion width has not beenattained, and is not within the tolerance range, the method proceeds tostep S912, in which the controller 220 determines an adjustment to bemade to one or more of, a rocking angle range, or a radial headposition, adapted to attain the preset edge exclusion zone width. Instep S914, the controller 220 sends control signals to the polishing arm301 and head 304 to move and/or rotate according to the determinedadjustment. Polishing may then be performed. After step S914, the methodcycles back to step S910. If in step S910, it is determined, by thecontroller 220, that the edge exclusion zone width has been attained, oris within a tolerance range, the method ends in step S916. In someembodiments, actual edge exclusion width is not checked for eachsubstrate (e.g., is only checked initially, periodically or at someother time(s), if at all).

The foregoing description discloses only exemplary embodiments of theinvention. Modifications of the above disclosed apparatus and methodswhich fall within the scope of the invention will be readily apparent tothose of ordinary skill in the art. For instance, although only examplesof cleaning a round substrate are disclosed, the present invention couldbe modified to clean substrates having other shapes (e.g., a glass orpolymer plate for flat panel displays). Further, although processing ofa single substrate by the apparatus is shown above, in some embodiments,the apparatus may process a plurality of substrates concurrently.

Accordingly, while the present invention has been disclosed inconnection with exemplary embodiments thereof, it should be understoodthat other embodiments may fall within the spirit and scope of theinvention, as defined by the following claims.

1. A method of controlling a width of an edge exclusion zone on asubstrate comprising: determining a range of angles over which to rotatea polishing head; rotating the polishing head over the determined rangeof angles to achieve a preset width for an edge exclusion zone of thesubstrate; and polishing an edge of the substrate with the polishinghead.
 2. The method of claim 1 further comprising: determining whetherthe preset width of the edge exclusion zone has been achieved; andadjusting the range of angles over which to rotate the polishing head toachieve the preset width for the edge exclusion zone based on thedetermination of whether the preset width of the edge exclusion zone hasbeen achieved.
 3. The method of claim 1 further comprising: applying apolishing tape to the substrate via the polishing head during polishingto achieve the preset width of the edge exclusion zone.
 4. The method ofclaim 1 further comprising: operating the polishing head via acontroller.
 5. The method of claim 1 wherein the polishing head includesa backing roller.
 6. The method of claim 5 further comprising: pressingthe backing roller against a polishing tape to contact the substrate. 7.The method of claim 2 further comprising: measuring an actual edgeexclusion width to determine whether the preset width of the edgeexclusion zone has been achieved.
 8. The method of claim 7 furthercomprising: comparing the actual edge exclusion width to the preset edgeexclusion width to determine whether the preset width of the edgeexclusion zone has been achieved.
 9. The method of claim 7, furthercomprising measuring the actual edge exclusion width via one or moresensors.
 10. A method of controlling a width of an edge exclusion zoneon a substrate comprising: determining a radial position at which toplace a polishing head with respect to a substrate so as to achieve apreset width of an edge exclusion zone for the substrate; moving thepolishing head to the determined radial position; and polishing thesubstrate with the polishing head.
 11. The method of claim 10 furthercomprising: determining whether the preset width of the edge exclusionzone has been achieved; and adjusting the radial position of thepolishing head to achieve the preset width of the edge exclusion zonebased on the determination of whether the preset width of the edgeexclusion zone has been achieved.
 12. The method of claim 10 furthercomprising: rotating the polishing head when the polishing head is incontact with the substrate.
 13. The method of claim 12 furthercomprising: applying a polishing tape to the substrate via the rotatingpolishing head to achieve the preset width of the edge exclusion zone.14. A method of controlling a width of an edge exclusion zone on asubstrate comprising: providing a polishing head having a head spacerand a backing roller coupled to the head spacer at an off-centerposition and adapted to apply a polishing tape to a substrate duringpolishing; and applying the polishing tape to an edge exclusion zone ofthe substrate using the polishing head during polishing.
 15. The methodof claim 14 further comprising: determining whether a preset width ofthe edge exclusion zone has been attained; and adjusting at least one ofa range of angles over which to rotate the polishing head and a radialposition of the polishing head based on the determination of whether thepreset width of the edge exclusion zone has been attained.
 16. Themethod of claim 14 further comprising: operating the polishing head viaa controller.
 17. The method of claim 15 further comprising: measuringan actual edge exclusion width to determine whether the preset width ofthe edge exclusion zone has been attained.
 18. A system for controllinga width of an edge exclusion zone on a substrate comprising: a polishinghead having a head spacer, wherein the polishing head is adapted tocontact an edge of a substrate; a backing pad coupled to the head spacerat an off-center position; a polishing arm coupled to the polishinghead; and a controller adapted to operate the polishing head andpolishing arm to control an edge exclusion zone of the substrate. 19.The system of claim 18 further comprising a polishing tape, wherein thepolishing head is adapted to press the polishing tape against the edgeof the substrate.
 20. The system of claim 18 wherein the polishing headis adapted to angularly translate at different angles about the edge ofthe substrate.
 21. The system of claim 18 wherein the polishing arm isadapted to move to accommodate exclusion zones with different widths.22. The system of claim 18 wherein the backing roller is adapted toapply a polishing tape to the substrate edge during polishing.